1. Field of the Invention
The present invention relates to a method of, and a tamping machine for, correcting the position of a railroad track composed of laterally adjacent track sections connected by branch tracks.
2. Description of the Prior Art
U.S. Pat. No. 4,947,757 describes the simultaneous operation by two tamping machines to work a switch or crossing section of a track, the switch section being formed by two track sections extending parallel to one another and a branch track connecting the same. The tamping machines are positioned adjacent to one another on the respective track sections and are working in tandem, being connected to one another by means of a control cable to enable the track lifting operation on both track sections to occur synchronously. This is to take into account the fact that the switch section, due to the branch track and the long ties connecting the two track sections, constitutes a structural unit, and that the switch section should consequently and expediently be lifted in its entirety only.
U.S. Pat. No. 5,493,499 discloses the use of the so-called "Global Positioning System" (GPS) in the context of correcting the position of a track by means of a tamping machine. A number of stationary satellite receivers are provided in place of the--heretofore customary--fixed track reference points, the position of the satellite receivers having been established with sufficient accuracy on an absolute basis. In addition to said stationary satellite receivers, a further satellite receiver is mobile together with the tamping machine on the track to be corrected. With the aid of this mobile satellite receiver, it is possible to convert the measured relative position of the track into absolute coordinates.
Finally, it is known from European patent application EP 0 722 013 A1 to measure the actual position of a track to be treated relative to a neighboring track by using the latter as a reference. Thus it is possible to reproduce the actual track position after it has been destroyed by the working operation of the machine.